This invention relates to an incrementally-adjustable wiring tray of the type used to contain and protect electrical cabling such as metal wiring or optical glass fiber communication cable. Wiring tray elements are ordinarily sold in incremental lengths. It is the responsibility of the installer to determine the length of the run and select the necessary elements that, collectively, make up the correct length. This often requires shortening one or more tray elements by cutting, and when the required run length is greater than the longest available length, telescoping or otherwise fastening two tray elements together to form a wiring tray of the correct length.
This invention permits predetermined lengths of tray elements to be joined to a very high degree of precision without cutting to make up a wiring tray having a correct length.